Field of the Invention
The present invention relates to a pneumatic tire that offers an improved traveling performance on an icy road while maintaining steering stability on a dry road and wear resistance.
Description of the Related Art
In order to improve traveling performance on a icy road, Japanese patent application laid-open No. 2011-162022 discloses a pneumatic tire having a tread block provided with two dimensional sipes that divide the tread block into a plurality of block-pieces with edges for scratching the icy road surface. Typically, the two dimensional sipe comprises a pair of sipe surfaces each of which uniformly extends to a bottom of the sipe while keeping its direction and opening configuration. The adjacent block-pieces divided by the two dimensional sipe are usually easy to deform each other through the sipe surfaces when the tire is subjected to friction force on the road, such that each edge of the block-pieces provides high friction force by scratching the icy road surface.
However, the large deformation of block-pieces causes loss of ground contact area of the tread block, whereby steering stability of the tire on dry roads and wear resistance of the tread block tends to deteriorate.